Reconciling organizational and cellular discrepancies between the mammalian and the avian cerebellum

• Author / Creator

  Craciun, Iulia

• Birds and mammals have highly developed cerebella. There are many similarities at both the cellular level and the systems level between these classes, although there are some apparent differences. In this thesis, we explored two of these discrepancies. The first is a difference at the systems level. Mammalian literature has determined that climbing fibres, originating from the inferior olive, innervate the cerebellum such that a particular subnucleus will only innervate either zebrin II immunopositive (ZII+) or zebrin II immunonegative (ZII-) stripes. Seemingly contrary this this scheme, avian literature has found that ZII+ and ZII- stripes of a functional pair are innervated by a common region of the inferior olive. Through retrograde tracing techniques, we demonstrate that ZII+ and ZII- are in fact innervated by separate, but adjacent areas of the inferior olive, thus aligning with the mammalian schematic organization. The second apparent difference we explore is one at a cellular level. Lugaro cells, which are well-characterized inhibitory interneurons in the mammalian cerebellum, have never been definitively described in an avian species. Here, we propose the existence of the avian Lugaro cell based on a number of similarities between these and mammalian Lugaro cells. The shared characteristics include fusiform somata with dendrites emerging from either end, residence in the granule cell layer just below the Purkinje cell layer, collateral innervation by Purkinje cells, and long axonal projections into the molecular layer akin to the parallel fibres of granule cells. In conclusion, these data highlight the similarity between with cerebella in birds and mammals at both the cellular and systems levels.

• Subjects / Keywords

  • cerebellum
  • immunohistochemistry
  • zebrin
  • inferior olive
  • Lugaro cells
  • optic flow

• Graduation date

  Spring 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-62p4-br92

• License

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